Moisten the soil, then lay clear plastic tarps over the soil for 4-6 weeks during the hottest part of the summer. Daytime temperatures need to be at least 80 degrees, F. for it to be warm enough.
effects can be improved by using a second layer of clear plastic, and by incorporating poultry litter prior to solarization; also, brassica cuttings or residue has a fumigation effect (biofumigation), if they are also incorporated before laying the plastic down.
Only effective in the top 12 inches of soil.
This method also kills beneficial soil biology, which is competing for resources with the pest nematodes. When done solarizing, make sure to add compost, composted manure, and/or compost tea to bring biological activity back up.
For effective solarization, moisten the soil, then cover it with a clear, plastic tarp. Leave the tarp in place for 4 to 6 weeks during the hottest part of summer.
The effectiveness of solarization is reduced in cool coastal areas, where summer temperatures commonly remain below 80°F.
For a complete discussion of solarization, see Soil Solarization listed in References. (UC Davis IPM)